Circuit-breaker operating system



.Aug. 4,1942, c. THUMIM ETAL CIRCUIT-BREAKER OPERATING SYSTEM briginalFiled Feb. 6, 1940 2 Sheets-Sheet l CLOSE OPEN I /09 Inventors: CariThumim, Edward J. Frank Al xander C. Boisseau Their Afztwneg Aug. 4,1942. c. THUMIM ETAL 2,292,096

' CIRCUIT-BREAKER OPERATING SYSTEM Or1g1na ".zled Feb. 6, 1940 2Sheets-Sheet 2 "was" 90 i .1 g I L \l il I j 50 5.9 H r 77 umu v 79inventmmsj Qari Thumim Edward J. Frank,

Patented Aug. 4, 1942 2,292,09 CIRCUIT-BREAKER orsaa'rmc SYSTEM CarlThumim and Edward J. Frank, Yeadon, and

Alexander 0. Boisseau, Lansdowne, Pa, assignor to General ElectricCompany, a corporation of New York Original application February 6,1940, Serial No. 317,564. Divided and this application April 4, 1941,Serial No. 386,920

7 Claims.

Our invention relates to circuit-breaker operating systems and moreparticularly to a tripfree fluid-actuated operating mechanismconstructed so that the means to be actuated, such as the circuitbreaker, can be released with respect to the fluid-actuated operatingmechanism during the course of th closing stroke and prior to completionthereof.

This application is a division of our application Serial No. 317,564,filed February 6, 1940,

A further object of our invention is to provide a fluid-operatedgas-blast circuit breaker in which trip-free operation is provided atany time during the operating cycle of the circuit breaker.

Further objects and advantages of our invention will become apparent asthe following de scription proceeds and the features of novelty whichcharacterize our invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of our invention, reference may be had to theaccompanying drawings in which Fig. 1 is a partly diagrammatic layout ofan operating system for a fluidoperated gas-blast circuit breakerembodying our invention, Fig. 2 is a cross-sectional view of the blastvalve shown schematically in Fig. 1, and

.Fig, 3 is a sectional view of the blast valve taken on line 3-4 of Fig.2.

Referring now to the drawings, we have illustrated our invention asapplied to a fluid-operated circuit breaker III of the cross gas-blasttype comprising a stationary contact ll and a, movable contactjl2arranged to be operated so as to draw air-arc in an arc chute 13. Thefixed contact II is connected to the line terminal ll while the movablecontact i2 is connected to the line terminal IS. The fixed contact II isprovided with spring pressed contact fingers Ha and longer arcingcontact fingers I! while movable contact I2 is Provided with an arcingtip l2 so that, when the contacts separate, an arc therebetween occursbetween arcing tips II' and I2. Immediately after separation of thecontacts, one terminal of the arc isgtransierred by and air or gas-blastthrough conduit I6 from contact fingers II to the contact II" which isprovided with a tip of arc-resistant metal. The air or gas blast fromconduit l6 upon opening of the breaker drives the are into the arc chutel3 against the edges of a plurality of partitions I-l in the arc chute,which partitions are transverse to the arc gap and th ends of whichextend close to the path of movement of the arcing tip [2 of the movablecontact l2. The circuit breaker I0, illustrated by way of example inorder to describe the operating system better, is not our invention butis described and claimed in United States Letters Patent 2,284,842,granted June 2, 1942, upon the joint application of David C. Prince,William K. Rankin, and Wilfred F. Skeats, and assigned to the sameassignee as the present application.

In order to produce relative movement between contacts II and 12 byfluid pressure, we provide,

a fluid-operated motor comprising a cylinder l8 and a piston l9operatively connected to movable contact l2 by means of connectin rod20. This connecting rod 20 comprises two parts 20' and 20" joined withone another by a lost-motion connection 2| arranged to operate atripping means 22 for releasing latch 23 which hold the circuit breakerIII in the closed position. For high-speed opening of circuit breaker[0, it is desirable to release some form of energy-storage means to aidthe fluid pressure in the opening operation. Latch 23 is provided inorder to hold energy-storage means 24 comprising a spring in the chargedcondition. This energy-storage means or spring 24 is charged orcompressed by fluid pressure during the closing movement of circuitbreaker l0 and latch 23 cooperating with member. 25 restrains thecircuit breaker and energy-storage means 24 in the closed and chargedpositions, respectively, until upward movement of piston i9 causesmember 26 of lostmotion connection 2| to engage with tripping means 22whereby latch 23 is released.

In order to operate piston i9, and, consequently, also movable contacti2 in response to fluid pressure, we provide a reserve fluid-pressuretank 21 which is connected to a fluid-pressure supply system through anonretum valve. not shown, soils to trap suflicient fluid which, forexample, may be air, at a suitable pressure to permit at least oneoperating cycle independent of the main fluid-pressure supply.Therefore, it the main fluid air supply should fail for any reason, oneoperating cycle of circuit breaker ll may still be obtained by virtue ofthe air or other fluid trapped in reserve tank 11. Reserve tank 21 isprovided with a pressure switch, indicated schematically at 2| ascomprising a sylphon bellows 29 connected to the reserve tank 21 andoperatively connected to a suitable double-throw switch 3. cooperatingwith a plurality of contacts Ila and 30b which will be describedhereinafter in greater detail.

Fluid-pressure tank 21 is connected by means of a conduit ii to amanifold 32 from which the fluidpressuremaybeadmittedtoeitherend ofcylinder ll in accordance with the operation of either circuitbreaker'opming valve 33 or circuit breaker clodng valve ll. Opming valveaisnormaliyheldinthepositimindioatedinPlg.i,closingoneendotmanitoldflagainst the fluidpressure tromconduit Iibymeansol arelativelyhe'avyspring llactingonlever associated withopening valve 31' Valve is arrangedtobeoperatedbyopeningsoiaioid 31,which also operates its own seal-in switch a. Openin valveIlinitsopmpositionisadapted to close escape port a through which fluidbelow piston I! may escape during the closing operation oi the circuitbreaker ll.

Similarly, closing valve ll is normally held in the position indicatedin Fig. 1, closing the other end '01 manifold 32 against the fluidpressure from conduit II by means of a relatively heavy spring ll actingon lever ll associated with closing valve ll. Lever ll, however,comprises two parts lid and lib, both mounted on a flxed pivot M, and,hence, diflers from lever ll associated with opening valve ll in amanner which will be described in greaterdetail hereinafter. Closingvalve ll is arranged to be operated by closing solenoid l2 which alsooperates its own sealin switch l3. Closing valve ll in its open positionis adapted to close escape port ll through which fluid above piston I!may escape during the opening operation of circuit breaker l0.

Trip-free operation of circuit breaker it is obtained by virtue of thefact that lever ll associated with closing valve ll and closing solenoidl! is constructed of two parts lia and lib which are held together as asingle lever by means of latch l pivotally mounted on member lib andadapted to engage with an extension on member lia. A relatively lightspring l6 is provided closing solenoid l! is still energized and holdinglever lib downwardly against the tension of relatively light spring ll.

It is evident that the reversal of the direction 01' piston ll duringthe trip-free closing stroke can be greatly expedited ii the backpressure on the closing or upper end oi piston II is reducedinstantaneously to a practicable minimum. Accordingly, we providebetween the openings in cylinder II and the respective opening andclosing valves 33 and ll a dumping valve l! which is arranged to providea very large opening to atmosphere for the upper end of cylinder llduring the opening operation 01' circuit breaker II. This dumping valvell comprises a relanectedtoapistoniloithesameorlargerdiameter,reciprocable in a cylinder 52 andnormaliybiasedbymeansoispringlltohoiddumpingvalvememberilintheclosedposition.erativdywithpiston 8| isa second valvememberllassodatedwithescapeportllwhich is normally open when dumping valvemunbcrllisclosedsoastoallowairoriiuiddr tromthelowerendotcylinderlltoeaeaps ainthesamemannerasportlland.inadditionthereto.duringtheclosingmovement arrangement, the upper end ofcylinder II has to bias member lib in such a direction that latch l5 mayengage the extension on member lia. It

will be understood, 01 course. that suitable spring means will beprovided for latch l5 so as normally to tend to rotate itin acounterclockwise direction to engage-with the extension of member lla.By the arrangement just described, lever ll acts as a unitary memberwhen clodng solenoid l2 is energized to open closing valve ll and,hence, to cause closing of the circuit breaker iii. If, however, duringthe closing operation of the circuit breaker, opening solenoid 31 shouldbe energized through any cause, such, for example, as an abnormalcurrent condition in the power circuits ll and i5, opening valve 33 willbe operated. In order to obtain rapid closing the pressure thereininstantaneously reduced so that rapid opening operation of circuitbreaker ll may be obtained.

The cross gas blast for arc-extinguishing purposes in arc chute I3 isalso obtained from reserve fluid-pressure tank 21 through blast valve 58and conduit ii. Blast valve 5 of the balanced pressure type, shown indetail in Figs. 2 and 3, is illustrated as mounted directly belowreserve pressure tank 21 and comprises a streamlined valve member 51which allows fluid pressure from tank 21 to pass through annularpassageway ll to conduit ll leading to are chute ll. Conduit II isillustrated in Fig. 2 as mounted at an angle with respect to blast valvell in order to provide additional space for illustrating the details ofthe control mechanism therefor. Valve member 51 cooperates with areplaceable valve seat 51' which is mounted in a casing ll enclosing acylinder 6i within which piston ll operatively connected to valve member51 reciprocates. Piston 60 is preferably flexibly connected with valvemember 51 for the purpose of self-alignment and is provided with a valveguide 82 reciprocating in a sleevelike member I. A spring member Gl isplaced between sleeve member 63 and valvev member 51 normally to tend tohold said valve member in the closed position. Cylinder 8|, sleevelikemember 63, and

spring member 64 are supported centrally by radial ribs 65 bridgingacross annular air passage 58.

The upper end of cylinder 6| is closed by a plate 66 to which isfastened a metallic striking plate 61. plate 61 and plate 66 is aflexible buffer disk 68 to cushion the opening of blast valve 56. The.

Between the metallic striking for opening valve 51 as will beset forthin,

greater detail hereinafter. A small passage 16 is provided in piston -68to interconnect th)e cylinder 6| on either side of piston 69 and, hence,to balance the pressures operating on the upper and lower surfaces understeady-state conditions. The area of piston 60 is relatively largecompared to the area of valve member 51 so that a considerably, lowerpressure operating on piston 60 may overcome a higher pressure operatingon valve member 51.

In order to open blast valve 58, a pilot valve ll of relatively largediameter is opened, rapidly releasing the pressure on the upper side ofpiston 60, whereby an unbalance of the pressure on piston 60 is obtainedand the fluid pressure operating against the under side of piston 60 issuflicient to overcome the forces holding valve member 5! closed, whichcomprise the fluid I pressure acting on the back of valve member 51 andspring means 64. Thereupon valve member 51 is forced open rapidly andpiston .66 contacts with striking plate 61 whereupon check valve 12closing port I3 in piston 60 is opened by virtue of the extension Hthereon which engages with striking plate 61. The upper surface ofpiston 68 is recessed at so that fluid pressure either through smallpassage 19 or port 18 within which check valve 12 operates is dis- Idecrease the volume of space 69 determined only by the clearancenecessary for valve member 51. Furthermore, the area of pilot valve IIhas been made as large as practicable and this combinabolted at 19 and80, respectively, to casing 59. Pilot valve H is held in the closedposition by means 0 spring mechanism 8| supported by U-sha member 18 andincluding adjustable means 82 by which the closing force on pilot valve1| may be adjusted to just overcome the normal fluid pressure in space69 tending to open pilot valve 1|. Movement of pilot valve, 1| againstthe force of spring mechanism 8| is effected through a pair of levers83. pivotally mounted at 84 to U-shaped member 11 and interconnected byblock 85 provided with an opening 86 through which rod 81 for operatingpilot valve H is connected. This opening 86 in block 85 is enlarged ateither end thereof so 'as to prevent any binding action between rod- 81and block 85 during the pivotal movement of levers 83. Pivotal movementof levers 83 is obtained either by the leftward pull of armature 88 ofopening air-blast solenoid 89 or by the leftward thrust of armature 90of closing airblast solenoid 9|. Pivotally mounted levers 83 areconnected in clevislike fashion to armature 88 at 92 while an extension93 provided with a roller 94 is connected to armature 90 of closingair-blast solenoid 9| so that movement of armature 99 may be transmittedthrough roller 94 and armature 88 to pivotally mounted members 83 foroperating pilot valve H. Solenoids 89 and 9| are coaxially mounted andconnected to one another by means of U-shaped plates 95. The entireapparatus including solenoids 89 and 9| is supported from casing 59 as aunitary,

structure by member 96. I

Pivotally mounted levers 83 are provided with a roller 91 which tends tohold a switch 98 in the open position whenever pilot valve 1| is closed.The contacts of switch 98,'however, are biased to the closed position byspring means 99 so that, whenever the opening air-blast solenoid 89 isenergized, switch 98 is closed after which opening operation of thecircuit breaker I0 is initiated. By this arrangement, switch 98 insuresthat the opening air blast for circuit breaker I0 is provided beforeopening of the circuit breaker may take place.

Certain features of our invention disclosed in 6 'this applicationrelating to blast valve 56 per se tion has enabled us to obtain anoperating speed I much higher than was possible heretofore.

Check valve I2 is provided so that pressure in space 69 may be built uprapidly when pilot valve 1| is closed so that valve member 51 is snappedshut in a minimum period of time. The extension ll on check valve 12 issufliciently long so that check valve 12 is maintained in the openposition for a reasonable length of time to prevent fluttering of thevalve member 51.

It will be understood by those skilled in the art that operation ofpilot valve ll requires considerably less operating force than would berequired to open blast valve 51 directly. The pilot valve H andoperating mechanism I6 therefor are mounted as a complete constructionalunit in are described and claimed in a copending application, Serial No.345,810,'filed July 16, 1940,

which application is a division of this application.

In order to control the operation of opening valve 33, closing valve 34,and blast valve 56, we provide anelectrical control system including asource of direct-current potential lflll. This source of controlpotential is connected to closing solenoid 42 through pressure switch30, contacts 30a, closo" button NH, and mechanically operated cut-offswitch. I82 which is arranged to be closed by cam member )3 when circuitbreaker I0 is open and which opens at the end of the closing strokeofcircuit breaker I0. Switch I02 for mechanically cutting ofi solenoidclosing coil 42 is provided with a holding coil I04 for preventingpumping of the circuit breaker III in the event that it is closed uponan abnormal current condition and the operator fails to release closebutton |0|. At a predetermined point in the closing stroke of circuitbreaker l0, switch I05 which is open in both the closed and openpositions of the circuit breaker is closed by virtue of cam member I06mounted on connecting rod 20 whereby closing air-blast solenoid 9| isenergized for producing a blast of arc-extinguishing fluid in arc chutel8 by virtue of the movement oi. armature 88 which operates pilot valveII and, hence, also valve member 81 of blast valve 88. Mechanicallyoperated switch I88 for controlling the closing air blast is closedbefore contacts II and I8 meet and opens after the contacts haveengaged. As has been mentioned before. closing solenoid 88 is providedwith a seal-in switch 88 i so that the operator may release "closebutton Ill prior to the completion of the closing operation.

Tripping operation of the circuit breaker may be initiated in one ofthree ways, either by manual operation of open" button I81, by automaticclosure of protective relay I88 which is energized from currenttransformer I88 associated with power line l8 whenever an abnormalcurrent condition occurs therein, or by the bridging of contacts 88b ofpressure relay switch 88 in the event the pressure in reserve tank 81falls below a predetermined minimum. All threeof these tripping meansare connected in parallel with one another but, in any event, openingsolenoid 31 cannot be energized until switch 88 has been closed which isaccomplished by the operation of protective relay I88, manually operableopen" button I81, or pressure relay 88 through the energization 08opening airblast solenoid 88 through mechanically cut of! switch llli.This switch 8 opens during the opening stroke of the circuit breaker l8by virtue of cam ill attached to connecting rod 88 and cuts off theopening air blast at the proper moment after the arc drawn has beenextinguished. As soon as opening air-blast solenoid 88 is energized,switch is closed and opening solenoid 81. is energized throughmechanical cutofl switch H8 which is closed at the beginning of theclosing stroke by virtue of cam I88 mounted on connecting rod 88 andopens at the end of the opening stroke of circuit breaker I8. As wasmentioned above, opening solenoid 81 is provided with a seal-in switch88 to insure completion of the tripping operation even though "open"button I81, protective relay I88, or pressure responsive relay '88bridging contacts 88b are immediately opened.

An auxiliary switch H8 is provided in series with signal means 8 which.for example, maycomprise a green light to indicate that the circuitbreaker is in the open position. Switch H8 is closed when circuitbreaker I8 is open and is opened mechanically by means of cam 8 onconnecting rod 88 when circuit breaker I8 is in the closed position. Asignal means 8 which. for example, may comprise a red light'is providedand is energized through opening air-blast solenoid 88 and mechanicallyoperated cuteofl switch 8 for opening air-blast solenoid 88 when thecircuit breaker I8 is in a closed position. It will be understood bythou skilled in the art that the resistance of signalmeans H8issuchastoallowonlyaverysmallcurrent t flow through this circuit whichis insumclent tocausesolenoidlltopullarmaturefltothe left and. hence.initiate tripping of circuit breaker l8. A signal means I" is alsoprovided in series with relay switch 88 and contacts 880 to indicate thecondition of the fluid pressure in reserve tank 81. If, for any reason,the pressure in reserve tank 81 should fall below a predeterminedamount, sylphon bellows 88 will contract opening contacts 88a so thatclosing of the circuit breaker if it is in the open position isprevented. Furthermore, closing of contacts 881; will energize theopening air-blast coil 88 and initiate tripping operation of the circuitbreaker in the event that it is in the closed position.

Although we have described our invention as applied to a single-polecircuit breaker, it will be understood by those skilled in the art thatit may equally well be applied to a multiple circuit breaker in whichcase blast valve 58 would be connected to a suitable manifold todistribute the fluid pressure to the different arc chutes of themultipole circuit breaker and connecting rod 88 would be adapted tooperate a plurality of poles instead of only a single one.

The operation of our invention will be described with reference to Fig.1 when the circuit breaker I8 is in the closed position as indicated.Tripping operation of the circuit breaker may be initiated in one ofthree ways; namely, if the operator manually depresses open" button I81,if an abnormal current condition occurs in power line l8 causingenergization of protective relay I88, or if the pressure in reservepressure tank 81 decreases sumciently so that pressure relay 88 causesswitch 88 to bridge contacts 88b. If either of these three situationsoccur, opening blast solenoid 88 is energized from control circuit I88through mechanical cutofl' switch H8. thus pulling armature 88 thereofto the left and opening pilot valve II as is evident from Fig. 2. Theopening of pilot valve II will allow the pressure in space 88 todecrease rapidly so that the pressure balance on piston 68 is disturbedand valve 51 is opened, allowing a blast of fluid from tank 81 to passthrough conduit i8 into arc chute I8.- This fluid blast occurs beforethe initiation of the opening operation of circuit breaker l8. As soonas opening blast solenoid 88 is energized and armature 88 is pulled tothe left, switch 88 is closed, allowing opening valve solenoid 81 to beenergized both to close its seal-in switch 88 and to open opening valve88 while closing escape port 88. This allows fluid under pressure fromtank 81 and manifold 88 to enter the lower end of cylinder 18.Furthermore, this fluid pressure moves piston ll ofdumping valve 88upwardly to close escape port 88 and provide a very large opening toatmosphere at the upper end of cylinder l8 so that high-speed opening ofcircuit breaker i8 may take place. The initial upward movement of pistonl8 by virtue of lost-motion connection 8| causes member 88 to engagetripping means .88, whereby latch 88 is released from member 88 andenergy-storage means 84 is released to aid the fluid-pressure means inhigh-speed opening of circuit breaker l8. As the circuit breaker l8reaches a predetermined podtlon in the opening stroke, cutoff switch 8is opened. thereby deenergizing opening air-blast solenoid 88 wherebypilot valve II is closed by spring means 8| and check valve I8 allowsfluid pressureto enter space 88 and cause valve member 81 to snap to theclosed position. Further movement in the opening direction of connectingrod 88 causes cutofl switch H8 to open the energization circuit ofsolenoid 81, whereby Opening valve 88, is forced shut by relativelyheavy spring 88. Auxiliary switch 8 is allowed to close and energizesignal means III for indicating that the circuit breaker is in the openposition.

To close the circuit breaker when it is in the open position. "close"button "I is operated and.iithepressureintank8'lissuiilcientlyhlgh sothat pressure relay 28 allows switch 30 to bridge contacts 30a, closingsolenoid 42 is energized through mechanically operated cutofl switchI02, which is in the closed position when circuit breaker I is open. Theenergization of closing solenoid 42 causes seal-in switch 43 to closeand, furthermore, causes opening of closing valve 34 and closing ofescape port 44 against the force of relatively heavy spring 40. Thisallows fluid under pressure from manifold 32 to enter the upper end ofcylinder I8. Since the area of piston I is at least as large as that ofvalve member 50 of dumping valve 49, valve member 50 is maintained inthe closed position by the force of spring 53 and piston I9 is forceddownwardly, charging. energy-storage means 24 and moving circuit breakerID to the closed position. Fluid underneath piston I9 is allowed to exitto atmosphere through escape ports 39 and 55. At a predetermined pointprior to the meeting of contact tips II and I2, cutofl' switch I05 forclosing air-blast solenoid 9| is closed, whereby armature 90 is moved tothe left opening pilot valve II 'and operating blast valve 56 in themanner described above to produce a blast of gas or air transverse ofcontacts II and I2 prior to the closing thereof. .After contacts II andI2 have engaged one another, cutofi switch I05 is opened, deenergizingclosing airblast solenoid 9| and, hence, allowing spring 4 means 8I toclose pilot valve II, whereby blast means H4 and signal means H6 isenergized through opening air-blast solenoid B9 and cutofl switch IIOtherefor which has been closed as the circuit breaker reaches the closedposition. The trip-free operation of the circuit breaker will beunderstood by those skilled in the art in view of the detaileddescription given above and will only be briefly mentioned hereinafter.If during the closing operation of the circuit breaker described in thepreceding paragraph, protective relay I08 should initiate a trippingoperation which it may do as soon as mechanical cutofi switch III! isclosed, the tripping operation described above will be initiated andenergization of opening solenoid 31 will occur,

whereby lever 35 causes rod 41 to engage projection 48 of latch 45allowing member a to pivot and close closing valve 3,4 by virtue ofrelatively heavy spring 40 even though solenoid 42 is still energized.Hence, trip-free operation is obtained and rapid opening of circuitbreaker I0 is accomplished.

It will be apparent to those skilled'in the art that our invention isnot limited to ,the particular construction shown but that changes andmodifications may be made without departing from .the spirit and scopeof our invention and we aim in the appended claims to cover all suchchanges and modifications.

What we claim as new and desire tosecure by Letters Patent of the UnitedStates is:

1. In an operating system for an electric circuit breaker comprisingaplurality of relatively movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said motor, means for connecting said source offluid with said fluid motor for closing said circuit breaker, means foropening said circuit breaker, and means interposed between said fluidmotor and said first-mentioned means operable during the openingmovement of said circuit breaker for instantaneously reducing the backpressure against said fluid motor so that high-speed opening operationof said circuit breaker may be obtained.

2. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a source .of fluid underpressure, means operable by said fluid under pressure for producingrelative movement between said contacts, a plurality ofsolenoid-operated valves for selectively connecting said source of fluidwith said last-mentioned means for closing and opening said circuitbreaker, and means interposed between said means operable by said fluidunder pressure and said plurality of solenoidoperated valves operableduring the opening movement of said circuit breaker for instantaneouslyreducing the back pressure against said means operable by said fluidpressure to a practicable minimum.

3. In an operating system for an electric circuit breaker comprising aplurality of relative- 1y movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said motor, valve means for connecting saidsource of fluid with said fluid motor for closing said circuit breaker,means for opening said circuit breaker, and a dumping valve ofrelatively large diameter interposed between said valve means and saidfluid motor operable during the opening movement of said circuit breakerfor very rapidly reducing the back pressure against said fluid motorthat high-speed opening operation of said circuit breaker may beobtained, said dumping valve being so constructed and arranged as toremain closed during the closing operation of said circuit breaker.

4. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said motor, a first valve for connecting saidsource of fluid with said fluid motor for closing said circuit breaker,a second valve for connecting said source of fluid with said fluid motorfor opening said circuit breaken'said valves being so con-. structed andarranged as to control exhaust ports associated with said fluid motor,solenoid means for operating each of said valves, a dumping valve ofrelatively large diameter including operating means comprising aspring-biased piston interposed between said fluid motor and said firstand second valves, said piston being operable by said source of fluidfor holding said dumping valve in a closed position during the closingoperation of said circuit breaker but arranged to open said dumpingvalve during the opening movement of said circuit breaker forinstantaneously reducing the back pressure against said fluid motorWhereby high-speed opening operation of .said circuit breaker may beobtained, and means associated with said dumping valve to preventopening thereof during the closing operation of said circuit breaker.

5. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said motor, means for connecting said source offluid with said fluid motor for operating said circuit breaker, andmeans interposed between said fluid motor and said first-mentioned meansfor substantially instantaneously relieving the fluid pressure tendingto retard the reversal of said fluid motor comprising means including adumping valve operable to theopen position in response to the forceexerted thereon by the fluid under pressure which causes reversal ofsaid fluid motor.

6. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a fluid motor comprising acylinder and piston for producing relative movement between saidcontacts, a source of fluid under pressure for operating said motor,means for connecting said source of fluid with said motm for closingsaid circuit breaker, and means interposed between said fluid motor andsaid flrstmentioned means ior rapidly relieving the fluid pressuretending to retard the reversal of said fluid motor to open said circuitbreaker including a dumping valve operable in response to the forceexerted thereon by the fluid under pressure causing reversal of saidfluid motor to open a large escape port between said cylinderand'atmosphere.

'I. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a source or fluid underpressure, a fluid motor comprising a cylinder and piston arranged to beconnected to said source,-

means operatively relating said piston to said circuit breaker, a largevalve in said cylinder arranged tovent quickly to atmosphere the fluidpressure acting to move said piston in one direction. fault-responsivemeans for initiating the opening of said circuit breaker, and means foropening said large valve immediately after the operation of saidfault-responsive means to permit trip-free operation of said circuitbreaker and high-speed opening thereof.

CARL THUMIM.

EDWARD J. FRANK.

ALEXANDER C. BOISSEAU.

